Question

Modern theory of evolution is based on:
(a) Mutations
(b) Genetic recombination
(c) Natural selection
(d) All of the above

Answer 1

Hint: Darwin who proposed the theory of natural selection as an explanation for evolution did not know much about the mechanism of genetics. The modern theory of evolution combines the knowledge of genetics with natural selection to explain evolution.

Complete Answer:
The modern synthetic theory describes a unified theory that resulted from the combination of Darwin’s theory of Natural selection with Mendelian genetics. It describes the evolution in terms of genetic changes occurring in a population due to mutations during sexual reproduction and their inheritance in the next generation and how natural selection selects the beneficial mutations to help an organism become better suited for its environment. Modern or Synthetic theory of evolution was introduced by J.B.S Haldane, R.A. Fisher, Sewall Wright, G.L Stebbins, Ernst Mayr, and many more evolutionary biologists.
The modern synthetic theory is based on the following:
Mutations: Mutations are known as changes that occur in the genome of an organism that results in the production of different proteins and thus altered phenotype. A mutation can occur during DNA replication, transcription, etc.
Heredity: The inheritance of variations from parents to their offsprings is known as heredity.
Reproductive Isolation: Reproductive isolation is known as the phenomena in which there is some sort of barrier which prevents reproduction between individuals of a species.
Genetic recombination or variation: There is recombination occurring during gamete formation in which mixing of homologous chromosomes takes place to give rise to new recombinant genotypes and phenotypes.
Natural selection: Natural selection is the process by which advantageous mutations are selected to help an organism survive better in its environment.
So, the correct answer is '(d) All the above'

Note: Darwin came up with the theory of natural selection with Alfred Wallace.
Both Darwin and Alfred Wallace came up with the same conclusions about natural selection independently based on their observations in South America. Ernst Mayr is the scientist who came up with the definition of biological species and he is known as the ‘Triple Crown of Biology’.